| 摘要 |
PURPOSE:To obtain a bipolar transistor having emitter diffused regions with two different depths, by effecting doping of phosphorous from openings for emitters opened in an oxide film formed on an epitaxial layer, forming emitter diffused regions by a first heat treatment, and then effecting a second heat treatment after removing an oxide film on some of the emitter diffused regions. CONSTITUTION:Openings 6 for emitters and an opening 7 for a collector lead region are formed in an SiO film 5 provided on the surface of an epitaxial layer 2 by photolithography. Phosphorus is doped into each of the base diffused regions 4 and epitaxial regions 21, 22. Subsequently, a first heat treatment is carried out in a wet O1 atmosphere. A phosphosilicate glass layer 10 on one emitter diffused region 8 is removed by photolithography using a photoresist 11, and a second heat treatment is then effected. In consequence, ordinary redistribution diffusion is effected in the emitter diffused region 8 from which the phosphosilicate glass layer 10 has been removed, while, in the other emitter diffused region 8, redistribution diffusion is affected deeper by rediffusion of phosphorus from the phosphosilicate glass layer 10. |
